Strengthened the dense alumina ceramics by flash treatment

In this paper, we report that the hardness of alumina ceramics can be enhanced by flash treatment. The effects of treatment conditions on the hardness of dense alumina ceramics were studied. The results show that as the current density increases, the hardness first increases and then decreases; and the highest hardness is more than 20% higher than that of the original sample. The microstructure analysis reveals that flash-treatment has two effects on alumina: (1) generation of dislocations, increasing hardness; and (2) generation of oxygen vacancies/pores, decreasing hardness. The variation of hardness with current density and treatment time is the combined result of these two effects. The current research provides a simple and feasible approach to strengthen alumina ceramics, which could be extended to other ceramic systems.